Fusaclean, produced on the base of nonpathogenic Fusarium oxysporumisolate Fo 47 , was used for preplanting treatment of substratum infested with Fusarium oxyspomm f. sp. dianthi and soaking of tulip bulbs and gladiolus tuber to protect them against F. oxysporum f. sp. tulipae and F. oxysporum f. sp. gladioli, respectively. Preplanting treatment of substratum prepared for carnation growth with the biocide in dose 2.5 g/1, significantly decreased the development of Fusarium wilt. Application of the biocide for soaking of tested bulb plants decreased the disease spread and increased yield of tulip bulbs.